Outdoor crown block door lock safety interlocking device
By installing limit switches and alarm circuits in parallel with electrical connections, the problem of poor contact of outdoor crane door locks in corrosive environments was solved, ensuring stable operation of the crane and timely alarms, thus improving the reliability of the equipment.
Patent Information
- Application Number
- CN202423090967.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2034-12-13
AI Technical Summary
Traditional outdoor crane door limit switches are prone to deformation and rust in corrosive environments, leading to poor contact and affecting the normal operation of the crane.
Two limit switches are installed in parallel and electrically connected, and equipped with an alarm circuit to ensure that the crane can still operate when at least one limit switch is working properly, and to trigger an alarm in case of a fault.
This effectively avoids overhead crane power outages caused by poor contact of a single door limit switch, ensuring stable equipment operation and providing timely maintenance reminders, thus improving equipment reliability.
Smart Images
Figure CN223867790U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to crane safety protection technology, and more specifically, it relates to a crane door lock safety interlock device for outdoor applications. Background Technology
[0002] Traditional outdoor overhead cranes use conventional mechanical door limit switches for their end beam doors and loading doors. While this is sufficient for outdoor production sites with some shelter, it is insufficient for production sites exposed to the elements or highly corrosive environments, where prolonged exposure to sun and rain can cause deformation, rust, and corrosion of the railings. Figure 1 The diagram shows the circuit structure of an existing overhead crane door lock safety device. When the door closes, the limit switch S1 is activated, triggering contactor KM1 to conduct. The crane's start and stop can be controlled by the stop switch S2 and the start switch S3. When the guardrail deforms, the crane experiences significant vibration during operation. This can easily cause malfunctions such as poor contact in the limit switch. Poor contact in the limit switch will activate the crane's passive protection mechanism, causing a power outage and preventing the crane from operating normally, thus affecting production. Utility Model Content
[0003] The technical problem to be solved by this utility model is to provide a safety interlock device for crane door locks that can be used outdoors to avoid the problem of cranes failing to work due to poor contact of the door limit switch.
[0004] This utility model discloses a safety interlock device for an outdoor crane door lock, comprising a contactor, a stop switch, a start switch, and a first limit switch installed on one side of the crane door frame; a second limit switch is installed on the crane door frame, and the second limit switch is installed in parallel with the first limit switch; one end of the first limit switch is connected to a power supply terminal, and the other end of the first limit switch is connected to the contactor through a first air switch; the second limit switch is connected to the connection terminal of the first limit switch and the power supply terminal, and the other end of the second limit switch is connected to the connection terminal of the contactor and the first air switch through a second air switch; an alarm circuit is connected to the connection terminals of the first limit switch and the first air switch, and the second limit switch and the second air switch.
[0005] Preferably, the alarm circuit includes an AND gate module, a signal amplification module, a relay, and an alarm light; the two input terminals of the AND gate module are respectively connected to the first circuit breaker and the second circuit breaker via a step-down voltage regulator module and a first threshold switch, and the output terminal of the AND gate module is connected to the input terminal of the signal amplification module, the output terminal of the signal amplification module is connected to one end of the relay coil, the common contact of the relay is connected to the power supply terminal, and the normally closed contact of the relay is connected to the alarm light.
[0006] Preferably, the step-down voltage regulator module includes a first rectifier, a first resistor, a first Zener diode, and a third resistor; an input terminal of the first rectifier and a connection terminal of a first threshold switch and a first air switch are connected; an output terminal of the first rectifier is connected to an input terminal of an AND gate module through the first resistor; and the connection terminal of the AND gate module and the first resistor is grounded through a first Zener diode and a third resistor connected in series.
[0007] Preferably, the connection terminal of the first threshold switch and the first air switch is connected to the input terminal of the first rectifier through the first varistor.
[0008] Preferably, the connection terminal between the AND gate module and the first resistor is grounded through the first filter capacitor.
[0009] Beneficial effects
[0010] The advantages of this invention are as follows: By installing two limit switches in parallel and connecting them in parallel, the crane door lock safety interlock device has the redundant function of two limit switches with the same function. During the use of the crane, if one limit switch fails or is disconnected due to an abnormal situation, and the other limit switch is still in the closed loop state, it is considered that the door is closed. This avoids the problem of the crane failing to work due to poor contact of the limit switch, and helps to ensure the stable operation of the equipment. Attached Figure Description
[0011] Figure 1 A schematic diagram of the circuit structure of an existing crane door lock safety device;
[0012] Figure 2 This is a schematic diagram of the circuit structure of the crane door lock safety interlock device of this utility model;
[0013] Figure 3 This is a schematic diagram of the alarm circuit structure of this utility model. Detailed Implementation
[0014] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention.
[0015] See Figure 2 This utility model discloses a safety interlock device for an outdoor crane door lock, comprising a contactor KM1, a stop switch S2, a start switch S3, and a first threshold switch S1 installed on one side of the crane door frame. A second threshold switch S4 is installed on the crane door frame, and the second threshold switch S4 is installed in parallel with the first threshold switch S1. One end of the first threshold switch S1 is connected to a power supply terminal, and the other end of the first threshold switch S1 is connected to the contactor KM1 through a first air switch DZ1. The second threshold switch S4 is connected to the connection terminal of the first threshold switch S1 to the power supply terminal, and the other end of the second threshold switch S4 is connected to the connection terminal of the contactor KM1 and the first air switch DZ1 through a second air switch DZ2. The connection terminals of the first threshold switch S1 and the first air switch DZ1, and the connection terminals of the second threshold switch S4 and the second air switch DZ2, are all connected to an alarm circuit.
[0016] This invention utilizes two limit switches installed in parallel and electrically connected in parallel to provide the crane door lock safety interlock device with redundant functionality of two limit switches with identical functions. During crane operation, if one limit switch malfunctions or disconnects due to an abnormal situation, and the other limit switch is still in a closed-loop state, the door is considered closed. This minimizes the risk of the crane failing to operate due to poor contact of the limit switches, ensuring stable equipment operation. The alarm circuit allows for immediate alarm activation when either limit switch malfunctions, alerting the operator to address the fault. An air switch between the limit switches and contactor KM1 provides signal isolation between the two switches, preventing interference with sampling and protecting the circuit itself.
[0017] The specific installation method for the threshold switch is as follows: Refer to the original installation foundation of the crane's threshold switch, cut a rectangular iron plate with a length of 120mm and a width of 100mm from a 6mm thick iron plate, and drill four Φ4mm holes at the four corners of the iron plate. Weld the prepared iron plate to the crane's door frame, so that the second threshold switch S4 is arranged side by side and perpendicular to the original threshold switch of the crane. After welding and fixing, when the door is closed, the two threshold switches can be activated simultaneously.
[0018] like Figure 3As shown, in this embodiment, the alarm circuit includes an AND gate module U1, a signal amplification module P1, a relay KT1, and an alarm light L1. The two input terminals of the AND gate module U1 are connected to the first air switch DZ1 via a step-down voltage regulator module and the first threshold switch S1, and the second threshold switch S4 is connected to the second air switch DZ2, respectively. The output terminal of the AND gate module U1 is connected to the input terminal of the signal amplification module P1. The output terminal of the signal amplification module P1 is connected to one end of the coil of the relay KT1. The common contact of the relay KT1 is connected to the power supply terminal, and the normally closed contact of the relay KT1 is connected to the alarm light L1. When the door is closed, both threshold switches are turned on, resulting in electrical signals at points A and B. These electrical signals are then processed by the step-down voltage regulator module and input as detection signals into the AND gate module U1. When both points A and B have detection signals (i.e., a value of 1), the AND gate module U1 outputs a control signal to the signal amplification module P1. This control signal is amplified by P1 and then sent to the coil of relay KT1, causing it to activate. This results in the normally closed contact of relay KT1 opening from the common contact, and the alarm light L1 not working. When either threshold switch or door is not closed, the AND gate module U1 has no output, causing the normally closed contact of relay KT1 to connect to the common contact, and the alarm light L1 to work. This achieves an alarm for threshold switch malfunctions, promptly reminding the driver to perform maintenance.
[0019] In this embodiment, the step-down voltage regulator module includes a first rectifier D1, a first resistor R1, a first Zener diode ZD1, and a third resistor R3. One input terminal of the first rectifier D1 and the first threshold switch S1 are connected to the connection terminal of the first air switch DZ1. One output terminal of the first rectifier D1 is connected to an input terminal of the AND gate module U1 through the first resistor R1. The connection terminal of the AND gate module U1 and the first resistor R1 is grounded through the first Zener diode ZD1 and the third resistor R3 connected in series. The rectifier converts AC power to DC power, and the step-down voltage regulator circuit composed of the first resistor R1, the first Zener diode ZD1, and the third resistor R3 ensures that the detection signal meets the input voltage requirements of the AND gate module U1.
[0020] In addition, the connection terminal of the first threshold switch S1 and the first air switch DZ1 is connected to the input terminal of the first rectifier D1 through the first varistor RV1, which serves as lightning protection. The connection terminal of the AND gate module U1 and the first resistor R1 is grounded through the first filter capacitor C1, which serves as filtering for the detection signal.
[0021] Since the circuit structures of the buck regulator modules between point A and AND gate module U1, as well as between point B and AND gate module U1, are identical, the circuit structure and working principle of the buck regulator module between point B and AND gate module U1 will not be described again. In this paper, both AND gate module U1 and signal amplification module P1 adopt existing circuit structures, such as the AND gate circuit structure based on the 74SL08 chip.
[0022] The working principle of this utility model is as follows: When the door is opened, both threshold switches are open, and contactor KM1 has no input. Stop switch S2 and start switch S3 are both disabled. When the door is closed, if both threshold switches are closed normally, contactor KM1 has input, stop switch S2 and start switch S3 are enabled, and points A and B both have electrical signal outputs. Both input terminals of door module U1 have detection signals, causing its output control signal value to be amplified by signal amplification module P1. After being amplified by signal amplification module P1, the control signal is sent to the coil of relay KT1 to activate it, causing its normally closed contact to open with the common contact, and alarm light L1 to stop working. When the door is closed, if either limit switch fails to close, the contactor KM1 will have input due to the parallel connection of the two limit switches, enabling both the stop switch S2 and the start switch S3. One input terminal of the AND gate module U1 will have no input, resulting in no control signal output. Consequently, the relay KT1 will not operate, and the normally closed contact of the relay KT1 will connect with the common contact, activating the alarm light L1.
[0023] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present utility model. These modifications and improvements will not affect the effectiveness of the present utility model or the practicality of the patent.
Claims
1. A safety interlock device for an outdoor crane door lock, comprising a contactor (KM1), a stop switch (S2), a start switch (S3), and a first threshold switch (S1) installed on one side of the crane door frame; characterized in that, A second threshold switch (S4) is installed on the crane door frame, and the second threshold switch (S4) is installed in parallel with the first threshold switch (S1). One end of the first threshold switch (S1) is connected to the power supply terminal, and the other end of the first threshold switch (S1) is connected to the contactor (KM1) through the first air switch (DZ1). The second threshold switch (S4) is connected to the power supply terminal of the first threshold switch (S1), and the other end of the second threshold switch (S4) is connected to the connection terminals of the contactor (KM1) and the first air switch (DZ1) through the second air switch (DZ2). An alarm circuit is connected to the connection terminals of the first threshold switch (S1) and the first air switch (DZ1) and the second threshold switch (S4) and the second air switch (DZ2).
2. The crane door lock safety interlock device for outdoor applications according to claim 1, characterized in that, The alarm circuit includes an AND gate module (U1), a signal amplification module (P1), a relay (KT1), and an alarm light (L1). The two input terminals of the AND gate module (U1) are connected to the first circuit breaker (DZ1) and the second circuit breaker (DZ2) via a step-down voltage regulator module and a first threshold switch (S1), respectively. The output terminal of the AND gate module (U1) is connected to the input terminal of the signal amplification module (P1). The output terminal of the signal amplification module (P1) is connected to one end of the coil of the relay (KT1). The common contact of the relay (KT1) is connected to the power supply terminal. The normally closed contact of the relay (KT1) is connected to the alarm light (L1).
3. A crane door lock safety interlock device for outdoor use according to claim 2, characterized in that, The step-down voltage regulator module includes a first rectifier (D1), a first resistor (R1), a first Zener diode (ZD1), and a third resistor (R3). An input terminal of the first rectifier (D1) and a first threshold switch (S1) are connected to a first air switch (DZ1). An output terminal of the first rectifier (D1) is connected to an input terminal of an AND gate module (U1) through the first resistor (R1). The connection terminal of the AND gate module (U1) and the first resistor (R1) is grounded through the first Zener diode (ZD1) and the third resistor (R3) connected in series.
4. A crane door lock safety interlock device for outdoor use according to claim 3, characterized in that, The first threshold switch (S1) and the first air switch (DZ1) are connected to the input terminal of the first rectifier (D1) through the first varistor (RV1).
5. A crane door lock safety interlock device for outdoor applications according to claim 3, characterized in that, The connection between the AND gate module (U1) and the first resistor (R1) is grounded through the first filter capacitor (C1).